The present invention relates to tubing hangers.
A tubing hanger is used in a well, for example an oil well, to suspend a length of tubing within a casing. The tubing hanger, with the tubing suspended beneath it, is lowered into a tubing head at an upper end of the casing and locked to the tubing head.
It is necessary to provide a seal between the exterior surface of the tubing hanger and the tubing head so that the annular space between the casing and the tubing is isolated. This allows the passage of fluids into and from this space.
It has previously been proposed to provide on the tubing hanger a seal which locates between the tubing hanger and the tubing head when the tubing hanger is locked to the tubing head. However, since the tubing hanger with the seal must be moved relatively to the tubing head into a position to be locked to the tubing head, the seal cannot engage the tubing head tightly.
According to a first aspect of the invention, there is provided a tubing hanger for an oil well comprising an exterior surface carrying an annular seal having a portion for engagement with a tubing head when the tubing hanger is located in a tubing head to prevent relative movement between the seal and the tubing head, the tubing hanger being movable axially relative to the seal when so engaged to bring the seal into sealing engagement with the tubing hanger and the tubing head to form an annular seal therebetween.
According to a second aspect of the invention, there is provided a method of sealing a tubing hanger in a tubing head comprising lowering a tubing hanger downwardly into a tubing head until an annular seal extending around the tubing hanger engages a shoulder on an interior surface of the tool head to prevent further relative movement between the seal and the tubing head, continuing said downward movement of said tubing hanger so that said tubing hanger moves relative to said seal, said relative movement forcing the seal into sealing engagement with the tubing head and the tubing hanger.